Before I get started... my friend Charlie's advice is better than mine, do what they say.
1. I think candid photography is fantastic. If you can train yourself to really pretend the camera isn't there, that's great.
2. Barring that, my goal is not to do some stiff rigid power pose (I do gravitate to some poses that tend to work, but I'm not as consistent about it as Charlie is), but to be comfortable and make people think I was born on camera, and that I'm equally natural and charming in person. Of course, I'm an awkward mess in person, so that leads me to...
3. Embracing goofiness. Taking photos of yourself is a little bit dumb, so let it be a little bit dumb. I write about fun poses here, in the context of menswear, but I think it's relevant to people who want to take photos. Eat on camera. Dance on camera. Interview a teddy bear on camera. Live your life well, and capture that, with every unusal beat it carries.